Pollock Survey – NOAA Teacher at Sea Blog

July 22, 2024July 24, 2024

Nick Lee: The Data, July 15, 2024

NOAA Teacher at Sea
Nick Lee
Aboard NOAA Ship Oscar Dyson
June 29 – July 20, 2024

Mission: Pollock Acoustic-Trawl Survey

Geographic Area of Cruise: Eastern Bering Sea

Date: July 15, 2024

Weather Data from the Bridge:

Latitude: 59° 51.9 N

Longitude: 173° 53.5 W

Wind Speed: 11 knots

Air Temperature: 6.1° Celsius (42.9° Fahrenheit)

Science and Technology Log:

On my cruise, scientists take acoustic measurements along the length of each transect. To ensure that they are accurately estimating the abundance of pollock, they take steps to separate out any backscatter that they believe didn’t come from pollock.

Scientists then apply algorithms to the data in order to estimate pollock abundance over the entire survey area. First, they break up the transect into 0.5 nautical mile (NM) sections and record the average backscatter for that section. Specifically, scientists are interested in the areal density – the amount of backscatter per square nautical mile (NM²).

This data can be challenging to interpret, so one way the scientists represent it visually is with a stick plot over the survey area:

Stick plot showing acoustic backscatter from the 2022 pollock survey. This is a simple map of the Bering Sea, where the land of Alaska appears in gray and the water is white with some bathymetric lines. The transect lines run straight, at a slight angle on this rotated map, across the waters. Yellow bars of different sizes stick up off the transect lines at an angle. — *Acoustic backscatter from the 2022 pollock survey.*

In this graphic, the transect lines are shown in black, and the density of acoustic backscatter for each 0.5 NM section is represented with a yellow stick. The longer the stick, the greater the density of backscatter at that location.

Scientists then use this data to perform calculations on the entire survey area, including the space in between transects. For each 0.5 NM section of transect, the acoustic density is extrapolated halfway to the next transect on either side.

Diagram showing transect lines, and how acoustic density is applied across the survey area. Three gray vertical lines, evenly spaced, are each labeled "transect line;" dotted lines mark the distance halfway between each transect line. A smaller portion of the middle transect line is colored red instead of gray. It's labeled with a parallel double-sided arrow marking out "0.5 nautical mile." A red box the height of that red section stretches as far to the left and right as the next dotted halfway line; one side is labeled "half distance to next transect." — In this diagram, the red line represents a 0.5 NM section of transect for which acoustic density is calculated. This acoustic density is then applied to the entire pink rectangle, which extends halfway to the next to the transect on either side.

By doing this process for every 0.5 NM section of transect studied, scientists are able to calculate values of acoustic density for the entire survey area.

Map of current survey area with transect lines and boxes showing the area over which transect data is extrapolated. — *Map of current survey area and transect lines (black), with boxes (purple) indicating the area over which data from each transect is extrapolated.*

Getting from acoustic density to pollock abundance takes another set of calculations, this time making use of trawl data. The pollock caught in each trawl can vary drastically in terms of size – some trawls are mostly juveniles, some trawls are mostly adults, and some are an even mix of both. For a given location, scientists use data from the nearest geographic trawl to estimate the distribution of fish in that area.

Distribution of pollock centered around 20-30 cm. This is a bar chart. The x-axis displays length in centimeters (0 to 80 cm) and the y-axis displays proportion of the catch (0 to 0.125). The majority of the bars are black, but a minor portion are colored partially red, indicating proportions of identified male pollock, or blue, indicating proportions of identified of female pollock. — *In some trawls, the most fish were within 20-30 cm in length (above) while in others, most fish were over 40 cm in length (below).*

Distribution of pollock centered around 40-50 cm. This is a bar chart. The x-axis displays length in centimeters (0 to 80 cm) and the y-axis displays proportion of the catch (0 to 0.125). The majority of the bars are black, but a minor portion are colored partially red, indicating proportions of identified male pollock, or blue, indicating proportions of identified of female pollock.

Having trawl data is necessary to convert the acoustic data into fish abundance because small and large pollock do not reflect backscatter equally. Scientists have studied this, and they have created a relationship for the different backscatter reflected by different length pollock. Using the distribution of pollock in the nearest trawl, scientists are able to proportionally allocate the observed backscatter to pollock of different lengths.

Graph showing that as pollock length increases, acoustic backscatter also increases. The x-axis shows pollock length in centimeters (0 to 80) and the y-axis shows acoustic size in "(TS, dB re 1 m2)", ranging from -50 to -30. A blue line curves gently from the lower right corner ("small fish, weak backscatter") to the upper right corner ("large fish, strong backscatter.") — *As pollock length increases, backscatter also increases.*
(Equation from Lauffenburger et al., 2023. Mining previous acoustic surveys to improve walleye pollock (Gadus chalcogrammus) target strength estimates, ICES Journal of Marine Science, Volume 80, Issue 6, August 2023, Pages 1683–1696, https://doi.org/10.1093/icesjms/fsad094)

As an example, let’s simplify the two locations sampled in the graphs above. Suppose the first location had only 20 cm pollock, the second had only 40 cm pollock, and equal backscatter was observed at both sites. Scientists know that, all else being equal, 20 cm pollock produce less backscatter than 40 cm pollock. This means that in order to reflect the same backscatter, there must be a greater number of 20 cm pollock than 40 cm pollock.

By repeating a similar process for each geographic location, scientists are able to estimate the number of pollock in the entire survey area!

Personal Log

The sailing and many of the operations of NOAA Ship Oscar Dyson are done by NOAA Corps officers. I hadn’t heard of the NOAA Corps before sailing, but I’ve since learned that they play an important role in facilitating NOAA research.

To learn more about the experience of NOAA Corps officers, I interviewed Ensign Savi Morales.

Ensign Savi Morales working with John Swenson, a member of the deck crew. Engisn Morales wears the blue every day uniform of the NOAA Corps and stands at a bank of navigational computers on the bridge. Both men gaze down at a display screen. — *Ensign Savi Morales (left) on the bridge collaborating with John Swenson, a member of the deck crew.*

Why did you decide to become a NOAA Corps officer?

I’ve always wanted to support the protection of the environment and mitigating climate change. After college, I was trying to figure out where I would contribute the most. I really loved being out on the water, and I had sailed plenty but I wanted to find a way to combine my interests in an environment I contribute the most. The NOAA Corps felt like it was a combination of those things.

I also loved the idea of working with the crew, engineering department, and science. I really enjoy that mixture of groups we have aboard Dyson, which makes every trip’s dynamic different. There’s also a lot of hands-on experience on the bridge deck making our 12 days packed with projects I work on. The NOAA Corps embraces a diverse skill set in order to think and act like a Swiss army knife and be a jack of all trades.

What are your responsibilities on board the ship?

My responsibilities are two 4-hour bridge watches as a Junior Officer of the Deck as I work towards becoming a fully qualified Officer of the Deck. In between my watches I work on tasks related to my responsibilities as the Dyson’s damage control officer, assistant navigation officer, and assistant public affairs officer. I track the sea service hours for our augmenting and personal crew, which they can use to upgrade their license. I maintain flags, and I do monthly safety rounds, inspecting fire extinguishers and fire stations.

What do you enjoy the most about your work?

I enjoy meeting the characters that come to the Dyson, definitely an eclectic but fun group. I also enjoy how much they’ve thrown me into the mix and had me figure things out. It’s a little bit of a trial by fire, but I learn really quick and I’d rather learn by doing.

What part of your job with NOAA did you least expect to be doing?

Checking fire extinguishers, there’s about 100 on board and they all need to be checked monthly. It takes about 3-4 hours.

Here in the Bering Sea you hear about the big, massive waves, but it’s not always like that. The Aleutian Islands are gorgeous with lots of wildlife. I don’t think I’ve seen this many bald eagles, orcas, or puffins in my entire life. They always brighten my day.

What advice do you have for a young person interested in a career in the NOAA Corps?

NOAA Corps requires you to have a four-year college degree in order to apply. Other than that, I’d say find opportunities to go out on the water. There’s high school scholarships, there’s college scholarships. You can also volunteer if you have time. I volunteered at the UC Davis Bodega marine lab. I visited once a week just to hang out with the scientists, with the crew to see if this is what I liked. Be curious and experience things for yourself!

Did you know?

NOAA Corps is one of the country’s eight uniformed services, and its officers operate NOAA ships and aircraft around the country. After completing basic training at the US Coast Guard Academy, NOAA officers assist in fisheries research, seafloor mapping, monitoring atmospheric conditions, and may respond to natural disasters and extreme weather. Learn more at the NOAA Corps website here!

July 16, 2024July 16, 2024

Nick Lee: In the Fish Lab, July 12, 2024

NOAA Teacher at Sea
Nick Lee
Aboard NOAA Ship Oscar Dyson
June 29 – July 20, 2024

Mission: Pollock Acoustic-Trawl Survey

Geographic Area of Cruise: Eastern Bering Sea

Date: July 12, 2024

Weather Data from the Bridge:

Latitude: 60° 02.17 N

Longitude: 176° 37.3 W

Wind Speed: 14 knots

Air Temperature: 5.5° Celsius (41.9° Fahrenheit)

Science and Technology Log

Once the trawl is completed, the codend is unloaded onto a conveyor belt for sorting. Usually, we just sort by species, picking out any organisms that aren’t pollock and storing them in separate baskets. Overall, I’ve been surprised with how “clean” or uniform the catches have been. We will usually have some jellyfish, but other than that we tend to have only a few fish of other species in a catch with hundreds or thousands of pollock.

Pollock on the conveyor belt. We can see the orange rain coats and long yellow gloves of two scientists standing nearby. — *The catch is first emptied onto a conveyor belt where it is sorted by species.*

When the catch has a mix of juvenile and adult pollock, we’ll also sort them by size, which roughly correlates to age group. The size cutoff used for sorting is only an approximation of age (the exact age is determined later), but it is still useful in ensuring that we sample a consistent number of each size class in every trawl.

Distinguishing between the larger juveniles and smaller adults on the belt can be tricky, so on one trawl we got creative and found what we named a “measuring fish.” This fish was the smallest length that had been designated as an adult in the previous trawls – anything smaller we left on the belt with the juveniles and anything larger we put in a separate basket with the adults. While not the most conventional solution, it served our purpose well and showed that anything can be made into a measuring instrument!

Nick is wearing a heavy orange rain coat and long yellow gloves. He holds up two pollock fish vertically, comparing their lengths to one another. We see more fish on a sorting table in the background. — *Using a “measuring” fish to sort the catch according to size (Photo Credit: Matthew Phillips).*

Once the fish are sorted, we take length and weight measurements for a representative sample of all species in the trawl. We measure the length of hundreds of pollock in a given trawl, so luckily the system is very efficient.

When I length a pollock, I’ll grab the fish in one hand and place it on the magnetic length board so that its head is against the end at zero. Then I’ll use my other hand to straighten the fish and place a magnet at the fork of the tail. The length board records where the magnet touches the length board, measuring what is known as the “fork length” of the fish.

Pollock on length board; its head faces toward the left side of the board, near a digital meter reading the length. toward the right side, a red magnet is placed at the fork of the fish's tail. — *The length board records where the red magnet is placed.*

For a subsample of pollock, we will also record the sex and maturity of each individual. To collect this data, we’ll first make a cut along the side of the pollock. This allows us to observe the pollock’s ovaries or testes and compare them to a chart showing the stages of development. Based on the time of year, most of the pollock we catch are in the “developing” stage. Also visible are the pollock’s liver and its stomach, which is often filled with krill!

Three people stand at a long metal table wearing heavy orange raincoats and gloves. White bins, a white cutting board, and a measuring board line the table. Matthew, in the foreground, holds a fish up with two hands over a measuring board, and looks at someone over his right shoulder. Nick, in the middle, looks down at the fish that Matthew holds, and a third scientist stands beyond Nick, looking on as well. — *Scientist Matthew Phillips showing me how to identify the sex and maturity of a pollock (Photo Credit: Mike Levine).*

For a subsample of the pollock in this group, we’ll also collect otoliths, which are similar to tree rings in that they allow scientists to visually determine the age of the individual. Otoliths are part of pollock’s inner ear, and they help the fish to detect vibrations in the water. Like tree rings, they grow throughout a fish’s life, adding visible layers each year. During times when the fish is actively feeding (usually during the summer), an opaque layer forms around the otolith. In contrast, when the fish is eating less, the otolith layer formed is translucent. By studying otoliths, scientists can determine the age of a fish, as one opaque layer and one translucent layer together represent one year. (Source: https://www.fisheries.noaa.gov/national/science-data/age-and-growth)

Teacher at Sea Nick Lee removing an otolith. Nick wears a heavy orange raincoat and long yellow gloves. He holds part of a pollock in his right hand and with his left hand holds up a small white object (the otolith) with tweezers. — *Extracting an otolith from the head of a pollock (Photo Credit: Mike Levine).*

One important and sometimes overlooked step in scientific data collection is the clean-up. At Codman Academy, we use the phrase “Leave No Trace,” and I try to model this idea in the fish lab as well. Working with fish can be smelly, and the smell only grows when fish are allowed to sit for extended periods of time. The process of recording sex and extracting otoliths can be especially messy, so we are constantly spraying down baskets and surfaces (and each other!) between data collection steps.

All of the fish that are processed are ultimately disposed of overboard – usually during the processing of the trawl dozens of seabirds follow the ship in search of discarded fish!

View through a doorway of an outer deck; over the railing we see seabirds flying past the fish lab. The sky and the water are gray. — *Seabirds flying past the fish lab.*

Personal Log

Outside of my stateroom, there is a tongue-in-cheek poster claiming to be a “Bering Sea Weather Guide.” The poster has the labels “Good Day,” “Some Days,” and “Other Days,” below paint swatches, all of them different shades of gray. There are also gray paint swatches for “Summer,” “Winter,” and “Days Ending in Y.”

"Bering Sea Weather Guide," a collection of gray paint swatches labeled: Most Days, Good Days, Some Days, Other Days, Last Week, Next Week, This Week, Days Ending in Y, Summer, Fall, Winter, Spring — *“Bering Sea Weather Guide” outside my stateroom.*

We’ve certainly had our share of gray days this cruise, and I’ve become used to falling asleep to the sound of the ship’s foghorn. However, we’ve also gotten a few moments of sunshine and blue sky, providing some great moments for bird and whale watching from the bridge. Being on the night shift, I’ve also been able to observe a couple of sunsets from the water!

View from the bridge on a clear day - blue skys, scattered fluffy white clouds — *View from the bridge on a clear day (left) and sunset at sea (right).*

Sunset behind NOAA Ship Oscar Dyson - nice mix of purples, pinks, blues, yellows — *View from the bridge on a clear day (left) and sunset at sea (right).*

Did you know?

Because we are so far north and west in the time zone, the sun sets very late here, usually around 1 am!

July 12, 2024August 8, 2024

Nick Lee: Fishing, Fishing, Fishing, July 10, 2024

NOAA Teacher at Sea
Nick Lee
Aboard NOAA Ship Oscar Dyson
June 29 – July 20, 2024

Mission: Pollock Acoustic-Trawl Survey

Geographic Area of Cruise: Eastern Bering Sea

Date: July 10, 2024

Weather Data from the Bridge:

Latitude: 50° 40.9 N

Longitude: 178° 29.9 W

Wind Speed: 20 knots

Air Temperature: 6.2° Celsius (43.1° Fahrenheit)

Science and Technology Log:

Last blog post, I talked about acoustic backscatter, which scientists on board use to locate fish. When scientists notice high-intensity backscatter – or backscatter that they’re interested in collecting more biological data about – they’ll call the bridge and ask to go fishing. The bridge then makes the announcement over the radio:

“All stations. This is the bridge. We will be fishing, fishing, fishing.”

This announcement sparks a flurry of action from scientists, NOAA officers, and the deck crew. A few scientists go up to the bridge for a marine mammal watch, where they make sure that there are no marine mammals in the area of the operation. NOAA officers navigate to the science team’s target fishing area, and the deck crew prepares the net to go in the water.

Teacher at Sea Nick Lee on marine mammal watch. Nick stands at a window on the bridge and looks out through binoculars at gray waters under a gray sky. — *Marine mammal watch on the bridge.*

Before my cruise, I thought fishing nets were relatively simple and uniform. However, I’ve since learned that the net has many different components and sensors, which help scientists collect additional information about the fish seen with acoustics.

Codend

During the trawl, the net is dragged behind the boat. Near the opening at the mouth of the net, the net’s mesh is over a meter wide. This helps reduce drag from the water, while still funneling fish toward the back of the net. The net gradually gets smaller until the very end of the net – called the codend – where the fish are collected. At the end of each trawl, the net is hauled out of the water, and the contents of the codend are emptied into a sorting table for further processing in the fish lab, where length, weight, sex, and maturity are recorded for a representative sample.

Pocket Nets

In portions of the net with larger mesh, small fish and other organisms can escape through the holes in the mesh. This creates a problem for scientists – a trawl could show that only adult pollock are present in a certain area when in reality the population is mixed, but all of the juveniles escaped! Since scientists will be using trawl samples to understand the overall population of pollock, they want to avoid bias as much as possible in their data.

To get around this problem, scientists are studying the rates at which different sized pollock (and other organisms) escape from the net. They use pocket nets, or small nets made of the same fine mesh as the codend, to get an idea of what escaped from each trawl. Nine pocket nets are attached to the side, top, and bottom of three different sections of the net with varying mesh sizes. As the trawl net is being hauled back on the boat, one of my jobs is to help empty these pocket nets and collect what’s inside.

We’ve mostly found krill and jellyfish, but occasionally we’ll find a larval fish or squid!

CamTrawl

Near the codend, there is also a camera, referred to as CamTrawl. This camera provides scientists with a visual of what is going into the net, and can be used to help identify species and length of fish that are caught.

Scientists deploying PelagiCam. View through a doorway of two scientists in orange foul weather gear and green and white hardhats standing close to one another at the railing of the ship. They face away from the camera. In the foreground, on the deck, is a spool containing yellow cable. — *CamTrawl (left) and scientists Matthew Phillips and Mike Levine deploying PelagiCam (right).*

On this cruise, scientists are also testing a camera that they lower over the side of the ship (without a net), known as PelagiCam. They are hoping that PelagiCam may be able to collect species and length data, supplementing the data captured when processing fish from the trawl. If PelagiCam can record this data accurately, it could provide an efficient complement to trawling, which requires a lot of time and collaboration between different teams of people.

Pollock seen on PelagiCam — *A pollock seen on PelagiCam (left). Posing with scientist Mike Levine in front of the PlagiCam (right).*

Teacher at Sea and scientist posing in front of PelagiCam. They are wearing foul weather gear and hard hats; Mike is also wearing a mask and gloves. — *A pollock seen on PelagiCam (left). Posing with scientist Mike Levine in front of the PlagiCam (right).*

FS70 Net Sounder

The FS70, nicknamed the Turtle, collects acoustic data and produces a live image of the net’s opening when it is in the water. This data allows scientists and the deck crew to monitor the shape of the net while fishing, ensuring that the net opened correctly. It also monitors when fish enter the net.

Live data from the FS70. a square screen mounted in a console displaying sonar data. — *FS70 (left), nicknamed the turtle, and the live data it shows scientists during a trawl.*

Personal Log:

Going fishing can sometimes be a lot of “hurry up and wait.” After the marine mammal watch, at least one scientist stays on the bridge to monitor the net using the FS70, and the others get ready to process the trawl. Letting the net out and hauling it back in is far from simple, however. It requires constant communication between the bridge and the deck crew, and it can be made more complicated by the weather or equipment malfunctions. Once the net is in the water, trawling can take anywhere from 15 minutes to over an hour.

Opening the codend is always exciting, because we’re never quite sure what we caught. While our target is always pollock, we’ll often find other interesting organisms mixed in as well. Some highlights include rockfish, squid, and a smooth lumpsucker.

close-up of a Rockfish in a white bin — *Organisms caught in the trawl so far include rockfish, squid, and smooth lumpsuckers.*

Squid in a white bin — *Organisms caught in the trawl so far include rockfish, squid, and smooth lumpsuckers.*

Did you know?

The net used on NOAA Ship Oscar Dyson was specifically designed for this survey!

August 29, 2023August 29, 2023

Germaine Thomas: Farewell to the Oscar Dyson and Summer, August 19, 2023

NOAA Teacher at Sea

Germaine Thomas (she/her)

Aboard NOAA Ship Oscar Dyson

August 7 – August 21, 2023

Mission: Acoustic Trawl Survey (Leg 3 of 3)
Geographic Area of Cruise: Pacific Ocean/ Gulf of Alaska
Date: Saturday, August 19, 2023

Weather Data
Lat 58.1 N, Lon 150.1 W
Sky condition: Partly Sunny
Wind Speed: 5.81 knots
Wind Direction: 346.98°
Air Temp: 12.91 °C

Science Log

The last trawl sample that the Oscar Dyson’s crew and scientist’s took was in deep water with a Methot net, named after Dr. Rick Methot, the NOAA scientist who developed it. This type of trawl net slows down the water as marine organisms tumble into it, so their delicate bodies are not crushed. The codend looks a lot like what you would see in a plankton tow, only it will catch a lot more organisms.

Micheal, wearing foul weather gear, yellow gloves, a hard hat, and a flotation jacket, stands on deck holding a net draped into a plastic bin. He turns his head to the side to look at the camera for a photo. Beyond, the sky is cloudy and the water is calm and gray. — Michal Levine as he removes the codend from the Methot trawl net

Sub-samples are taken from what the Methot catches. Some krill is preserved and sent back to NOAA in Seattle for identification and analysis. On board, the krill are weighed and counted. The krill and other organisms are small, so the tools used to sort them are designed for capturing and moving small organisms.

several strainers resting on a white table surface. two are rimmed circles with mesh centers. one is a standard kitchen strainer with a handle. we can also see a knife, a pencil, electrical tape, and a small torpedo-shaped device for measuring flow inside the net. — The tools used to sort krill

some krill (maybe 40, not thousands) displayed on a white surface — Krill

After the last krill was counted and weighed, the science team quickly jumped into action cleaning up the Fish Lab. Yes, I am including this in the science log, because cleanup is an important part of science that many high school students seem to forget.

view of cleaned equipment on the aft deck. Stacks of empty buckets, some suds still visible on the deck surface. a trawl net rests in a pile in the background. — Totes and baskets were scrubbed and then washed with a pressure hose

The crew had unreeled the trawl nets and were getting ready to ship them to Washington state.

trawl nets, orange and blue in color with ropes and buoys attached to them, sit in piles on deck beneath the large spools (now empty) where they had been mounted during the survey operations — Trawl nets neatly stacked on deck

Personal Blog

Being a Teacher at Sea on the Oscar Dyson was a fantastic way to end the summer for me. Shortly I will be heading back to Anchorage where high school has already started and students have already been to my class with a substitute teacher. I look forward to teaching school, but am so thankful for the opportunity to have this adventure.

It has been so wonderful working with the science team on this cruise. After so many unforeseen delays the objectives were met through team work and the organizational skills of the lead scientist Taina Honkalehto.

The people on this ship really enjoy working on the ocean. Whether it is captaining the boat, engineering, the mess, to programming echo sounders, identifying species of fish, weighing and sampling them, they all love what they do. They also really care about the work that they are doing, the health of the ocean, and they want to support the people working and living with it. Also, there is a unique brand of humor that comes with working together for extended periods of time at sea. You just have to laugh at strange fish that come aboard and wonder at the beautiful sunsets or northern lights.

two crewmembers wearing foul weather gear and large yellow gloves stand laughing at the sorting table in the wet lab. a woman holds a grenadier fish in two hands and closes her eyes in laughter while the man reaches toward the fish with something else (not discernable) in play. — A Grenadier fish

Germaine poses for a photo at the railing. the sun set creates nice pink and orange colors over a mountainous shoreline in the distance. — A Grenadier fish

On the bridge I found the ship’s communication flags. These flags are a way to communicate with other ships if the radios are not working or to hang on holidays with a message. When I was a kid back in Ketchikan, Alaska, I admired the flags so much I would draw cartoons with flag messages. So, to NOAA, the science team and the crew of the Oscar Dyson…

Germaine, wearing her Teacher at Sea hat, holds up a flag with horizontal bars in red, white, blue, meaning "T" — T

Germaine, wearing her Teacher at Sea hat, holds up a flag with white on top and red on the bottom, meaning "H" — H

Germaine, wearing her Teacher at Sea hat, holds up a flag with white on top and blue on the bottom, and a notch in the blue, meaning "A" — A

Germaine, wearing her Teacher at Sea hat, holds up a flag with blue and white checkers, meaning "N" — N

Germaine, wearing her Teacher at Sea hat, holds up a flag with blue on top and yellow on the bottom, meaning "K" — K

Germaine, wearing her Teacher at Sea hat, holds up a white flag with a blue square in the middle, meaning "S" — S

May the seas lie smooth before you. May a gentle breeze forever fill your sails. May sunshine warm your face, and Kindness warm your soul. – An Irish Sailor’s Blessing

August 28, 2023August 29, 2023

Germaine Thomas: Fish Reproduction and Why it’s Important, August 18, 2023

NOAA Teacher at Sea

Germaine Thomas (she/her)

Aboard NOAA Ship Oscar Dyson

August 7 – August 21, 2023

Mission: Acoustic Trawl Survey (Leg 3 of 3)
Geographic Area of Cruise: Pacific Ocean/ Gulf of Alaska
Date: Friday, August 18, 2023

Weather Data
Lat 58.18 N, Lon 148.82 W
Sky condition: Partially Cloudy
Wind Speed: 10.55 knots
Wind Direction: 32.58°
Air Temp: 14 °C

Science and Technology Blog

Meet Sandi Neidetcher, she is a fish biologist investigating fish reproductive status. Why care about fish reproduction? Well, the seafood industry is extremely important to Alaska and other coastal states. And they would not have an industry if those “little fishes” could not reproduce. But the ocean is changing due to climate and different types of pollution.

Climate change is making our oceans a warmer place—just a couple of degrees, but that may be enough to really change how fish reproduce and spawn. A few degrees in temperature could change when and where fish reproduce, and then cascade to the fishing industry, the food market, and the people who depend on them as food.

NOAA wants to have background information on fish reproduction so they can recognize whether the fish have changed their reproductive strategies over time and how that could impact fisheries.

Sandi received her Masters degree studying the ovaries of Pacific cod to determine the phenology and geography, or the timing and location, of spawning. She specialized in histology, which is the study of microscopic tissue structures, for her it was specifically the ovaries. To understand the reproductive process and ovary maturation, she studies slides with ovary tissue mounted and stained to show oocyte (unfertilized egg) structures that develop as the spawning season progresses.

a collection of eight histograms presented in two columns. each histogram displays a stained (artificially colored) cross-section of a piece of ovary tissue viewed on a slide under a microscope. in each slide, the tissue ranges from red to purple, with some gray; structures appear as circles, swirls, cells, unfortunately difficult for a lay person to describe helpfully. Germaine likely includes these as a general example of Sandi's research. The slides are labeled: 1) Immature (IMM) - reserve fund, tightly packed oocytes, little tunica, thin wall. 2) No development (ND) - reserve fund, more tunica, thick wall. 3) Developing (DEV) - Cortical Alveoli. 4) Vitellogenesis (VIT) - early to late vitellogenesis, nucelar migration, coalescence. 5) Prespawning (PSWN) - VIT plus hydration. 6) Spawning (SWN) - VIT, some hydration, plus post ovulatory follicles. 7) Partial Spent (PSNT) - VIT (no coalescence or hydration) plus post ovulatory follicles. 8) Spent (SNT) - early post ovulatory follicles, residual VIT resorbing. — Examples of histograms from Sandi’s research, showing the progression of Pacific cod oocyte structure development over the course of the spawning season

Now she is involved in a study looking at the reproductive states of Walleye Pollock. Pollock are multi-batch spawners. They have the ability to spawn (lay eggs) more than once in a season. So the female ovaries can be in different stages of reproduction throughout the season.

The first step in this analysis is to collect the ovaries from the pollock.

Sandi and Robert, wearing foul weather gear and long, yellow, heavy-duty gloves, stand at a work bench in the wet lab. Sandi, closer to the camera, holds a pollock in her right hand over a white cutting board. Robert, standing ready at the fish measuring board, looks down at the pollock Sandi is holding. — Sandi Neidetcher and Robert Levine work together to collect data on a pollock.

In the photo above, the fish will be measured for length and weight, then the ovary and the liver will be removed, weighed, and saved for analysis. The fish’s ear bones (otoliths) will also be removed and used to determine its age. Samples are sent back to Sandi at NOAA AFSC (Alaska Fisheries Science Center) in Seattle, Washington. Half of the ovary will be sent to a histology lab where technicians will prep the tissues and return the sides ready to be analyzed. The other half of the ovary is scanned on the ship.

Sandi is comparing the histological samples to Raman Spectroscopy Analysis that she does aboard the Oscar Dyson. A long time ago when I was an undergraduate student in chemistry, Raman spectrometers were very large. The one I worked with in my physical chemistry class was in the basement of a building on a special concrete slab that stopped any vibrations from disturbing the path of the laser. Did I mention that the whole setup took up almost half of the basement?

view of an equipment set up in the wet lab. the spectrometer (which Germaine has labeled in this photo) sits on a table to the left of the photo. the laser wand, connected to the spectrometer by a cable, rests nearby, adjacent to a small foil-covered plate holding a little blob of pink tissue. there's also a computer monitor displaying a graph of the readings. the table is a bit cluttered, with stacks of paper, a pair of goggles, a file box, a computer mouse. — The computer displays a scan of the ovarian tissue

Raman spectrometers have come a long way since my undergrad. Today, Sandi has a small wand that contains a laser connected to a spectrometer the size of a donut box. A small desktop computer connected to the spectrometer will give an immediate readout of the analysis.

The wand with the laser is held over the ovary to collect data on large macromolecules like lipids, proteins, and DNA.

two hands steady the laser wand over a bit of pink tissue resting on a foil-covered plate (itself on some paper towels.) the wand connects by a cable to the spectrometer, visible in the background. — You can see the laser light as it penetrates the ovary.

The analysis that Sandi does is to compare the molecular composition identified through the spectral patterns with the structures seen in the histology samples, and to determine if the maturation status can be identified through the spectral patterns. The ultimate goal would be to have a small hand-held spectrometer that a scientist could use right as the ovaries are extracted. This would greatly increase the amount of ovaries analyzed quickly and efficiently and reduce the cost and time required for histological analysis

Sandi sits at a table in the wet lab, turning to smile for the camera. She is wearing a gray NOAA logoed sweatshirt. A stack of a box and a binder (and some goggles) on the right end of her table - the foreground of the photo - obscure the view of what she is working on at the moment but this is likely the same table as the previous two photos. — Sandi at her work station on the *Oscar Dyson*

Pollock have variability in their reproductive strategies and may be impacted by environmental conditions. One strategy is down regulation, where a fish will reabsorb a number of eggs during maturation and, as a result, reduce the resources spent on reproduction. This reduces the fecundity, or number of eggs released by that fish in a season. Knowing how fecund a fish population is helps managers determine how many fish can be removed by a fishery. Atresia is the resorption of an oocyte and can be seen histologically. Mass atresia is where a whole ovary of oocytes is be reabsorbed. If the fish is not finding enough food or the temperature is not correct then, then a female fish can save energy by reducing, or stopping the whole process of reproduction.

Recent warming sea temperatures have been seen in the Gulf of Alaska, and this may be impacting fish reproduction. In 2020, the number of Pacific cod predicted had dropped so low that the federal waters fishery was closed. That same year, crew fishing for Pacific cod reported seeing a number of Pacific cod with mass atresia. Scientists do not know if the observation of atresia, during a warming period, is related to the population crash but studies like this will give more information for the future. Predicting population crashes that may be related to climate change, fish health or temperature differences are an important part of fisheries management and impact us all because the ocean is an important resource.

Personal Blog

Crew Members in the Spotlight

Juliette and Ben cross their arms and lean toward one another slightly to pose for a photo. They are standing in front of a wooden workbench with blue shelving containing small cubbies for nuts, bolts, other supplies. Two hard hats rest on top of the blue shelves. Juliette grips ear protection with her right hand. Ben wears a NOAA Ship Oscar Dyson t-shirt. — Pictured left to right, Juliette Birkner – Engineering, and Ben Boswell – Survey Technician

The Commanding Officer runs the ship, but there are many important jobs that the Oscar Dyson would not function without. Engineering is one of them. There is a small team of Engineers aboard that are constantly monitoring the ship when on shift.

Juliette is a member of the Oscar Dyson’s Engineering department and may have been on the staff the longest. Her personality is direct, friendly and capable. Before becoming an Engineer, she attained her bachelor of science degree at the University of Washington. After receiving her degree she did not really have a clear plan for a job. So she went to a community college and received the equivalent associates degree of a Junior Unlicensed Engineer. Eventually, through NOAA, she can be a fully qualified Engineer with time aboard ships.

Juliette has a wildly creative side and interest in science. The scarf she is wearing in the picture has different layers present in sedimentary rock. She is also a big fan of dinosaurs, placing several all over the ship for people to find when work is slow. Honestly, it is the kind of humor that keeps everyone moving around with a smile. Some dinosaurs even have sweaters that she knitted, in her down time. Her knitting is extremely impressive.

A stormtrooper figurine, riding a Tyrannosaurus Rex figurine, suspended from twine in front of a computer screen

a plastic dinosaur wearing a pink and blue knitted sweater, propped up on a metal surface against a wall

Ben is the Survey Technician for the ship. Survey Technician is the kind of job you would never know exists as a high school student. There are jobs out there in this world that people would never specifically train for in high school or college , but are highly needed where you have different groups collaborating in complex situations. Ben’s job description is a pretty long list; calibrate scientific instruments, collect data, assist scientists, help the deck crew, and act as a liaison between science and the deck crew.

How did he arrive at this position? He attained a bachelor of science in Wildlife Biology and worked in the field for a while. Unfortunately, he found the job hard to make a living with the low pay. Fishing’s siren song came in the form of factory trawling and other crew positions in smaller boats. Because of his academic training and work experience the “perfect storm” of a Survey Technician was born.

Soon we will be taking our last trawl sample and heading to port in Kodiak. There have been moments on the cruise where time crawled in the dead of night while I was struggling to stay awake. Mostly, it has been a trip of a lifetime, with an incredibly capable and adaptive team of scientists and crew members willing to share stories that keep you awake and lull you to sleep, dreaming about tomorrow.

panoramic view over the bow of NOAA Ship Oscar Dyson, from the flying bridge (the top most level); it's a beautiful day, with blue skies and wispy clouds — The view from the *Oscar Dyson’s* fly bridge